NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
609 
HOLOPORELLA DAMICORNIS, new species. 
Plate 77, figs. 1-7. 
Description. — The zoarium incrusts, first, the radicels of an alga to form an 
attachment for suspension; it then develops freely into a small irregular mass 
ornamented with horns of greater or less length. The superficial zooecia are little 
erect, simply oblique; the frontal is smooth and quite convex; it is terminated by 
an aviculiferous umbo more or less developed; the avicularium is open under the 
umbo toward the apertura. The apertura is semilunar, very finely crenulated; the 
anter is separated from the poster, which is smaller and concave, by two minute 
cardelles. The ovicell is hyperstomial, very salient, globular, smooth, provided 
with a large opening. The deep zooecia are rare ; they have no frontal : their umbo 
forms an interzooecial prominence. The interzooecial avicularia are large, ellip- 
tical, with pivot. The incomplete zooecia are suborbicular and not rare 
. r ha= 0.15 mm. 
Measurements. — Apertura , ,, „ 
L [/a=0.13 mm. 
Variations. — The zoarium with its eccentric shape is very curious; no one 
specimen resembles another and yet all have a general indefinable facies which 
permits their immediate determination. Evidently this is not altogether a phenome- 
non of symbiosis in its entirety, but it is very close to it. It is even probable that 
the alga chosen by the larva was always the same and that its disappearance has 
caused at the same time the death of the Cellepore. 
The umbo is rather fragile and is easily broken (fig. 6) ; often it is even not 
developed at all (fig. 5). 
Figure 7 shows the ordinary cumulation of the zooecia. Such sections indicate 
the complicated structure of the zooecial walls, which sometimes appear to con- 
tain dietellae. The interpretation of the sections of the Cellepores are really 
problems of descriptive geometry. 
Affinities. — In its zooecia this species somewhat resembles Ilolopordla albi- 
rostris Smitt, 1872, which still lives in the Floridan waters. It differs from it 
however in its symmetrical umbo and the absence of areolae. 
Occurrence. — Jacksonian (Zeuglodon zone) : Suck Creek, Clarke County, Mis- 
sissippi (rare); Cocoa post office, Choctaw County, Alabama (common); Jack- 
son, Mississippi (very rare). 
Cotypes. — Cat. No. 64222, TJ.S.N.M. 
HOLOPORELLA SEPARATA, new species. 
Plate 76, flgs. 13-19'. 
Description . — The zoarium is massive and is formed of small irregular masses 
fixed to bryozoa, to the convexity of shells, or to the radicells of algae. The super- 
ficial zooecia are erect, suborbicular, separated one from the other; the frontal is 
smooth. The apertura is orbicular and formed of a large, semilunar anter sepa- 
55893— 19— Bull. 108- 
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